Length-adjustable latch

Abstract

A length-adjustable latch having an outer housing and an inner housing. The length of the latch is adjusted by engaging an extension block of the inner housing with either of two positioned holes of the outer housing. A drive linkage connnects to a backset plate by engaging an extension element of the former with a sliding space of the latter. The combination of the drive linkage and the backset plate is encompassed by a spring but with either a trail end of the backset plate or both the rear portions of the backset plate and the drive linkage passing through each longitudinal opening of a slidable plate, the inner housing, an installation seat and the outer housing. Due to the manner of engagement between the inner housing and the outer housing and the corresponding position of the drive linkage and the backset plate, the length of the latch is adjustable, as desired, for a 60 mm (23/8") backset length or a 700 mm (23/4") backset length .

I claim: 
     
       1. A length-adjustable latch comprising: an outer housing (1) having an inwardly-extending protuberance (12) and having two longitudinally spaced holes (131,132) thereon;   an inner housing (3) having a longitudinal slot (31) to engage with said protuberance (12) and having an extension block (32) engageable with said positioned holes (131, 132), a circular slidable plate (4) being inserted thereinto;   an installation seat (2) being secured to said outer housing (1) by engaging two blocks (21) thereof with respective corresponding holes (11) disposed at said outer housing (1);   a drive linkage (5) having an extension element (52) extending from middle portion thereof; said drive linkage (5) being stepped at one end thereof to form a larger end and a smaller end; said larger end being connected to a U-shaped clip (51) and together inserted into a bolt (6); said smaller end being formed with an extension (53);   a backset plate (8) having a longitudinal sliding space (81) to slidably receive said extension element (52) of said drive linkage (5); said extension element (52) having a front end with a width slightly larger a width of said sliding space (81) to prevent said extension element (52) from sliding out of said sliding space (81); said backset plate (8) having a trail end (82) and a laterally protruding portion (821) on a rear end thereof;   a spring (54) encompassing said drive linkage (5) and said backset plate (8) being utilized to facilitate the operation of said bolt (6);   characterized in that:   said outer housing (1) is longitudinally slidable and adjustable relative to said inner housing (3) by positioning said longitudinally-spaced holes (131, 132) with said extension block (32);   said outer housing (1), said installation seat (21), said inner housing (3) and said slidable plate (4) each have respective openings provided on corresponding positions thereof respectively; said extension (53) of said drive linkage (5) extends through said openings provided respectively on the slidable plate (4), the inner housing (3) and the installation seat (2), the protruding portion (821) of the backset plate (8) is blocked out of the outer housing (1) by the installation seat (2);   said trail end (82) and said laterally protruding portion (821) of the backset plate (8) extend out of the installation seat (2), only said backset plate (8) is usable for drawing back said bolt (6) when said outer housing (1) is in a 70 mm backset position; said drive linkage (5) is utilized for drawing back said bolt (6) when said outer housing (1) is in a 60 mm backset position.